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<div class="title">thread.h</div>  </div>
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<div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno">    1</span>&#160;<span class="comment">// thread.h </span></div>
<div class="line"><a name="l00002"></a><span class="lineno">    2</span>&#160;<span class="comment">//  Data structures for managing threads.  A thread represents</span></div>
<div class="line"><a name="l00003"></a><span class="lineno">    3</span>&#160;<span class="comment">//  sequential execution of code within a program.</span></div>
<div class="line"><a name="l00004"></a><span class="lineno">    4</span>&#160;<span class="comment">//  So the state of a thread includes the program counter,</span></div>
<div class="line"><a name="l00005"></a><span class="lineno">    5</span>&#160;<span class="comment">//  the processor registers, and the execution stack.</span></div>
<div class="line"><a name="l00006"></a><span class="lineno">    6</span>&#160;<span class="comment">//  </span></div>
<div class="line"><a name="l00007"></a><span class="lineno">    7</span>&#160;<span class="comment">//  Note that because we allocate a fixed size stack for each</span></div>
<div class="line"><a name="l00008"></a><span class="lineno">    8</span>&#160;<span class="comment">//  thread, it is possible to overflow the stack -- for instance,</span></div>
<div class="line"><a name="l00009"></a><span class="lineno">    9</span>&#160;<span class="comment">//  by recursing to too deep a level.  The most common reason</span></div>
<div class="line"><a name="l00010"></a><span class="lineno">   10</span>&#160;<span class="comment">//  for this occuring is allocating large data structures</span></div>
<div class="line"><a name="l00011"></a><span class="lineno">   11</span>&#160;<span class="comment">//  on the stack.  For instance, this will cause problems:</span></div>
<div class="line"><a name="l00012"></a><span class="lineno">   12</span>&#160;<span class="comment">//</span></div>
<div class="line"><a name="l00013"></a><span class="lineno">   13</span>&#160;<span class="comment">//      void foo() { int buf[1000]; ...}</span></div>
<div class="line"><a name="l00014"></a><span class="lineno">   14</span>&#160;<span class="comment">//</span></div>
<div class="line"><a name="l00015"></a><span class="lineno">   15</span>&#160;<span class="comment">//  Instead, you should allocate all data structures dynamically:</span></div>
<div class="line"><a name="l00016"></a><span class="lineno">   16</span>&#160;<span class="comment">//</span></div>
<div class="line"><a name="l00017"></a><span class="lineno">   17</span>&#160;<span class="comment">//      void foo() { int *buf = new int[1000]; ...}</span></div>
<div class="line"><a name="l00018"></a><span class="lineno">   18</span>&#160;<span class="comment">//</span></div>
<div class="line"><a name="l00019"></a><span class="lineno">   19</span>&#160;<span class="comment">//</span></div>
<div class="line"><a name="l00020"></a><span class="lineno">   20</span>&#160;<span class="comment">//  Bad things happen if you overflow the stack, and in the worst </span></div>
<div class="line"><a name="l00021"></a><span class="lineno">   21</span>&#160;<span class="comment">//  case, the problem may not be caught explicitly.  Instead,</span></div>
<div class="line"><a name="l00022"></a><span class="lineno">   22</span>&#160;<span class="comment">//  the only symptom may be bizarre segmentation faults.  (Of course,</span></div>
<div class="line"><a name="l00023"></a><span class="lineno">   23</span>&#160;<span class="comment">//  other problems can cause seg faults, so that isn&#39;t a sure sign</span></div>
<div class="line"><a name="l00024"></a><span class="lineno">   24</span>&#160;<span class="comment">//  that your thread stacks are too small.)</span></div>
<div class="line"><a name="l00025"></a><span class="lineno">   25</span>&#160;<span class="comment">//  </span></div>
<div class="line"><a name="l00026"></a><span class="lineno">   26</span>&#160;<span class="comment">//  One thing to try if you find yourself with seg faults is to</span></div>
<div class="line"><a name="l00027"></a><span class="lineno">   27</span>&#160;<span class="comment">//  increase the size of thread stack -- ThreadStackSize.</span></div>
<div class="line"><a name="l00028"></a><span class="lineno">   28</span>&#160;<span class="comment">//</span></div>
<div class="line"><a name="l00029"></a><span class="lineno">   29</span>&#160;<span class="comment">//      In this interface, forking a thread takes two steps.</span></div>
<div class="line"><a name="l00030"></a><span class="lineno">   30</span>&#160;<span class="comment">//  We must first allocate a data structure for it: &quot;t = new Thread&quot;.</span></div>
<div class="line"><a name="l00031"></a><span class="lineno">   31</span>&#160;<span class="comment">//  Only then can we do the fork: &quot;t-&gt;fork(f, arg)&quot;.</span></div>
<div class="line"><a name="l00032"></a><span class="lineno">   32</span>&#160;<span class="comment">//</span></div>
<div class="line"><a name="l00033"></a><span class="lineno">   33</span>&#160;<span class="comment">// Copyright (c) 1992-1993 The Regents of the University of California.</span></div>
<div class="line"><a name="l00034"></a><span class="lineno">   34</span>&#160;<span class="comment">// All rights reserved.  See copyright.h for copyright notice and limitation </span></div>
<div class="line"><a name="l00035"></a><span class="lineno">   35</span>&#160;<span class="comment">// of liability and disclaimer of warranty provisions.</span></div>
<div class="line"><a name="l00036"></a><span class="lineno">   36</span>&#160;</div>
<div class="line"><a name="l00037"></a><span class="lineno">   37</span>&#160;<span class="preprocessor">#ifndef THREAD_H</span></div>
<div class="line"><a name="l00038"></a><span class="lineno">   38</span>&#160;<span class="preprocessor"></span><span class="preprocessor">#define THREAD_H</span></div>
<div class="line"><a name="l00039"></a><span class="lineno">   39</span>&#160;<span class="preprocessor"></span></div>
<div class="line"><a name="l00040"></a><span class="lineno">   40</span>&#160;<span class="preprocessor">#include &quot;copyright.h&quot;</span></div>
<div class="line"><a name="l00041"></a><span class="lineno">   41</span>&#160;<span class="preprocessor">#include &quot;utility.h&quot;</span> </div>
<div class="line"><a name="l00042"></a><span class="lineno">   42</span>&#160;<span class="preprocessor">#ifdef USER_PROGRAM</span></div>
<div class="line"><a name="l00043"></a><span class="lineno">   43</span>&#160;<span class="preprocessor"></span><span class="preprocessor">#include &quot;machine.h&quot;</span></div>
<div class="line"><a name="l00044"></a><span class="lineno">   44</span>&#160;<span class="preprocessor">#include &quot;addrspace.h&quot;</span></div>
<div class="line"><a name="l00045"></a><span class="lineno">   45</span>&#160;<span class="preprocessor">#include &quot;list.h&quot;</span></div>
<div class="line"><a name="l00046"></a><span class="lineno">   46</span>&#160;<span class="preprocessor">#endif</span></div>
<div class="line"><a name="l00047"></a><span class="lineno">   47</span>&#160;<span class="preprocessor"></span></div>
<div class="line"><a name="l00048"></a><span class="lineno">   48</span>&#160;<span class="comment">// CPU register state to be saved on context switch.  </span></div>
<div class="line"><a name="l00049"></a><span class="lineno">   49</span>&#160;<span class="comment">// The SPARC and MIPS only need 10 registers, but the Snake needs 18.</span></div>
<div class="line"><a name="l00050"></a><span class="lineno">   50</span>&#160;<span class="comment">// For simplicity, this is just the max over all architectures.</span></div>
<div class="line"><a name="l00051"></a><span class="lineno">   51</span>&#160;<span class="preprocessor">#define MachineStateSize 18 </span></div>
<div class="line"><a name="l00052"></a><span class="lineno">   52</span>&#160;<span class="preprocessor"></span></div>
<div class="line"><a name="l00053"></a><span class="lineno">   53</span>&#160;</div>
<div class="line"><a name="l00054"></a><span class="lineno">   54</span>&#160;<span class="comment">// Size of the thread&#39;s private execution stack.</span></div>
<div class="line"><a name="l00055"></a><span class="lineno">   55</span>&#160;<span class="comment">// WATCH OUT IF THIS ISN&#39;T BIG ENOUGH!!!!!</span></div>
<div class="line"><a name="l00056"></a><span class="lineno">   56</span>&#160;<span class="preprocessor">#define StackSize   (4 * 1024)  // in words</span></div>
<div class="line"><a name="l00057"></a><span class="lineno">   57</span>&#160;<span class="preprocessor"></span></div>
<div class="line"><a name="l00058"></a><span class="lineno">   58</span>&#160;</div>
<div class="line"><a name="l00059"></a><span class="lineno">   59</span>&#160;<span class="comment">// Thread state</span></div>
<div class="line"><a name="l00060"></a><span class="lineno">   60</span>&#160;<span class="keyword">enum</span> ThreadStatus { JUST_CREATED, RUNNING, READY, BLOCKED };</div>
<div class="line"><a name="l00061"></a><span class="lineno">   61</span>&#160;</div>
<div class="line"><a name="l00062"></a><span class="lineno">   62</span>&#160;<span class="comment">// external function, dummy routine whose sole job is to call Thread::Print</span></div>
<div class="line"><a name="l00063"></a><span class="lineno">   63</span>&#160;<span class="keyword">extern</span> <span class="keywordtype">void</span> ThreadPrint(<span class="keywordtype">int</span> arg);    </div>
<div class="line"><a name="l00064"></a><span class="lineno">   64</span>&#160;</div>
<div class="line"><a name="l00065"></a><span class="lineno">   65</span>&#160;<span class="comment">// The following class defines a &quot;thread control block&quot; -- which</span></div>
<div class="line"><a name="l00066"></a><span class="lineno">   66</span>&#160;<span class="comment">// represents a single thread of execution.</span></div>
<div class="line"><a name="l00067"></a><span class="lineno">   67</span>&#160;<span class="comment">//</span></div>
<div class="line"><a name="l00068"></a><span class="lineno">   68</span>&#160;<span class="comment">//  Every thread has:</span></div>
<div class="line"><a name="l00069"></a><span class="lineno">   69</span>&#160;<span class="comment">//     an execution stack for activation records (&quot;stackTop&quot; and &quot;stack&quot;)</span></div>
<div class="line"><a name="l00070"></a><span class="lineno">   70</span>&#160;<span class="comment">//     space to save CPU registers while not running (&quot;machineState&quot;)</span></div>
<div class="line"><a name="l00071"></a><span class="lineno">   71</span>&#160;<span class="comment">//     a &quot;status&quot; (running/ready/blocked)</span></div>
<div class="line"><a name="l00072"></a><span class="lineno">   72</span>&#160;<span class="comment">//    </span></div>
<div class="line"><a name="l00073"></a><span class="lineno">   73</span>&#160;<span class="comment">//  Some threads also belong to a user address space; threads</span></div>
<div class="line"><a name="l00074"></a><span class="lineno">   74</span>&#160;<span class="comment">//  that only run in the kernel have a NULL address space.</span></div>
<div class="line"><a name="l00075"></a><span class="lineno">   75</span>&#160;</div>
<div class="line"><a name="l00076"></a><span class="lineno"><a class="code" href="class_thread.html">   76</a></span>&#160;<span class="keyword">class </span><a class="code" href="class_thread.html">Thread</a> {</div>
<div class="line"><a name="l00077"></a><span class="lineno">   77</span>&#160;  <span class="keyword">private</span>:</div>
<div class="line"><a name="l00078"></a><span class="lineno">   78</span>&#160;    <span class="comment">// NOTE: DO NOT CHANGE the order of these first two members.</span></div>
<div class="line"><a name="l00079"></a><span class="lineno">   79</span>&#160;    <span class="comment">// THEY MUST be in this position for SWITCH to work.</span></div>
<div class="line"><a name="l00080"></a><span class="lineno">   80</span>&#160;    <span class="keywordtype">int</span>* stackTop;           <span class="comment">// the current stack pointer</span></div>
<div class="line"><a name="l00081"></a><span class="lineno">   81</span>&#160;    <span class="keywordtype">int</span> machineState[MachineStateSize];  <span class="comment">// all registers except for stackTop</span></div>
<div class="line"><a name="l00082"></a><span class="lineno">   82</span>&#160;    <span class="keywordtype">int</span>* id;</div>
<div class="line"><a name="l00083"></a><span class="lineno">   83</span>&#160;    <span class="keywordtype">int</span> numChildren;</div>
<div class="line"><a name="l00084"></a><span class="lineno">   84</span>&#160;    <a class="code" href="class_thread.html">Thread</a> *parent;</div>
<div class="line"><a name="l00085"></a><span class="lineno">   85</span>&#160;  <span class="keyword">public</span>:</div>
<div class="line"><a name="l00086"></a><span class="lineno">   86</span>&#160;    <a class="code" href="class_thread.html">Thread</a>(<span class="keywordtype">char</span>* debugName);        <span class="comment">// initialize a Thread </span></div>
<div class="line"><a name="l00087"></a><span class="lineno">   87</span>&#160;    ~<a class="code" href="class_thread.html">Thread</a>();              <span class="comment">// deallocate a Thread</span></div>
<div class="line"><a name="l00088"></a><span class="lineno">   88</span>&#160;                    <span class="comment">// NOTE -- thread being deleted</span></div>
<div class="line"><a name="l00089"></a><span class="lineno">   89</span>&#160;                    <span class="comment">// must not be running when delete </span></div>
<div class="line"><a name="l00090"></a><span class="lineno">   90</span>&#160;                    <span class="comment">// is called</span></div>
<div class="line"><a name="l00091"></a><span class="lineno">   91</span>&#160;</div>
<div class="line"><a name="l00092"></a><span class="lineno">   92</span>&#160;    <span class="comment">// basic thread operations</span></div>
<div class="line"><a name="l00093"></a><span class="lineno">   93</span>&#160;    <span class="keywordtype">void</span> Fork(VoidFunctionPtr func, <span class="keywordtype">int</span> arg);   <span class="comment">// Make thread run (*func)(arg)</span></div>
<div class="line"><a name="l00094"></a><span class="lineno">   94</span>&#160;    <span class="keywordtype">void</span> Yield();               <span class="comment">// Relinquish the CPU if any </span></div>
<div class="line"><a name="l00095"></a><span class="lineno">   95</span>&#160;                        <span class="comment">// other thread is runnable</span></div>
<div class="line"><a name="l00096"></a><span class="lineno">   96</span>&#160;    <span class="keywordtype">void</span> Sleep();               <span class="comment">// Put the thread to sleep and </span></div>
<div class="line"><a name="l00097"></a><span class="lineno">   97</span>&#160;                        <span class="comment">// relinquish the processor</span></div>
<div class="line"><a name="l00098"></a><span class="lineno">   98</span>&#160;    <span class="keywordtype">void</span> Finish();                  <span class="comment">// The thread is done executing</span></div>
<div class="line"><a name="l00099"></a><span class="lineno">   99</span>&#160;    </div>
<div class="line"><a name="l00100"></a><span class="lineno">  100</span>&#160;    <span class="keywordtype">void</span> CheckOverflow();               <span class="comment">// Check if thread has </span></div>
<div class="line"><a name="l00101"></a><span class="lineno">  101</span>&#160;    </div>
<div class="line"><a name="l00102"></a><span class="lineno">  102</span>&#160;    <span class="comment">// overflowed its stack</span></div>
<div class="line"><a name="l00104"></a><span class="lineno">  104</span>&#160;<span class="comment"></span>    <span class="keywordtype">int</span> <a class="code" href="class_thread.html#abf174c2c79bd83095255737ce3850417">Id</a>();</div>
<div class="line"><a name="l00106"></a><span class="lineno">  106</span>&#160;    <span class="keywordtype">void</span> <a class="code" href="class_thread.html#a6403215a0f5789b6b91b6baf6ccf5059">SetId</a>(<span class="keywordtype">int</span>);</div>
<div class="line"><a name="l00108"></a><span class="lineno">  108</span>&#160;    <span class="keywordtype">int</span> <a class="code" href="class_thread.html#a669e0ae7e3a2e355bcff39f2993ec31a">Children</a>();</div>
<div class="line"><a name="l00110"></a><span class="lineno">  110</span>&#160;    <span class="keywordtype">bool</span> <a class="code" href="class_thread.html#a614c9af3009c1e8fd75b1afb6b736739">isChild</a>(<span class="keywordtype">int</span>);</div>
<div class="line"><a name="l00111"></a><span class="lineno">  111</span>&#160;    </div>
<div class="line"><a name="l00114"></a><span class="lineno">  114</span>&#160;    <span class="keywordtype">void</span> <a class="code" href="class_thread.html#a4ff9e2024810a0795c409aa33f536a57">AddChild</a>(<a class="code" href="class_thread.html">Thread</a> *t, <span class="keywordtype">int</span> <span class="keywordtype">id</span>);</div>
<div class="line"><a name="l00116"></a><span class="lineno">  116</span>&#160;    <span class="keywordtype">void</span> <a class="code" href="class_thread.html#aea94203e7d5805e1da6c27285e992756">RemoveChild</a>(<span class="keywordtype">int</span> <span class="keywordtype">id</span>);</div>
<div class="line"><a name="l00118"></a><span class="lineno">  118</span>&#160;    <span class="keywordtype">void</span> <a class="code" href="class_thread.html#a52a2028c463f310ffddd75be2eea83e9">SetParent</a>(<a class="code" href="class_thread.html">Thread</a>* num);</div>
<div class="line"><a name="l00120"></a><span class="lineno">  120</span>&#160;    <a class="code" href="class_thread.html">Thread</a>* <a class="code" href="class_thread.html#aacfd1646f8c33d21d99e17a2ec0aeb49">GetParent</a>();</div>
<div class="line"><a name="l00121"></a><span class="lineno">  121</span>&#160;    <span class="keywordtype">void</span> setStatus(ThreadStatus st) { status = st; }</div>
<div class="line"><a name="l00122"></a><span class="lineno">  122</span>&#160;    <span class="keywordtype">char</span>* getName() { <span class="keywordflow">return</span> (name); }</div>
<div class="line"><a name="l00123"></a><span class="lineno">  123</span>&#160;    <span class="keywordtype">void</span> Print() { printf(<span class="stringliteral">&quot;%s, &quot;</span>, name); }</div>
<div class="line"><a name="l00124"></a><span class="lineno">  124</span>&#160;  <span class="keyword">private</span>:</div>
<div class="line"><a name="l00125"></a><span class="lineno">  125</span>&#160;    <span class="comment">// some of the private data for this class is listed above</span></div>
<div class="line"><a name="l00127"></a><span class="lineno">  127</span>&#160;<span class="comment"></span>    <span class="keyword">struct </span>node {</div>
<div class="line"><a name="l00128"></a><span class="lineno">  128</span>&#160;    <a class="code" href="class_thread.html">Thread</a> *c;</div>
<div class="line"><a name="l00129"></a><span class="lineno">  129</span>&#160;    <span class="keywordtype">int</span> pId;</div>
<div class="line"><a name="l00130"></a><span class="lineno">  130</span>&#160;    };</div>
<div class="line"><a name="l00132"></a><span class="lineno">  132</span>&#160;    node* c_Array;</div>
<div class="line"><a name="l00134"></a><span class="lineno">  134</span>&#160;    <span class="keywordtype">int</span> c_ArraySize;</div>
<div class="line"><a name="l00135"></a><span class="lineno">  135</span>&#160;    <span class="keywordtype">int</span>* stack;             <span class="comment">// Bottom of the stack </span></div>
<div class="line"><a name="l00136"></a><span class="lineno">  136</span>&#160;                    <span class="comment">// NULL if this is the main thread</span></div>
<div class="line"><a name="l00137"></a><span class="lineno">  137</span>&#160;                    <span class="comment">// (If NULL, don&#39;t deallocate stack)</span></div>
<div class="line"><a name="l00138"></a><span class="lineno">  138</span>&#160;    ThreadStatus status;        <span class="comment">// ready, running or blocked</span></div>
<div class="line"><a name="l00139"></a><span class="lineno">  139</span>&#160;    <span class="keywordtype">char</span>* name;</div>
<div class="line"><a name="l00140"></a><span class="lineno">  140</span>&#160;    <span class="keywordtype">void</span> StackAllocate(VoidFunctionPtr func, <span class="keywordtype">int</span> arg);</div>
<div class="line"><a name="l00141"></a><span class="lineno">  141</span>&#160;                        <span class="comment">// Allocate a stack for thread.</span></div>
<div class="line"><a name="l00142"></a><span class="lineno">  142</span>&#160;                    <span class="comment">// Used internally by Fork</span></div>
<div class="line"><a name="l00143"></a><span class="lineno">  143</span>&#160;</div>
<div class="line"><a name="l00144"></a><span class="lineno">  144</span>&#160;<span class="preprocessor">#ifdef USER_PROGRAM</span></div>
<div class="line"><a name="l00145"></a><span class="lineno">  145</span>&#160;<span class="preprocessor"></span><span class="comment">// A thread running a user program actually has *two* sets of CPU registers -- </span></div>
<div class="line"><a name="l00146"></a><span class="lineno">  146</span>&#160;<span class="comment">// one for its state while executing user code, one for its state </span></div>
<div class="line"><a name="l00147"></a><span class="lineno">  147</span>&#160;<span class="comment">// while executing kernel code.</span></div>
<div class="line"><a name="l00148"></a><span class="lineno">  148</span>&#160;</div>
<div class="line"><a name="l00149"></a><span class="lineno">  149</span>&#160;    <span class="keywordtype">int</span> userRegisters[NumTotalRegs];    <span class="comment">// user-level CPU register state</span></div>
<div class="line"><a name="l00150"></a><span class="lineno">  150</span>&#160;</div>
<div class="line"><a name="l00151"></a><span class="lineno">  151</span>&#160;  <span class="keyword">public</span>:</div>
<div class="line"><a name="l00152"></a><span class="lineno">  152</span>&#160;    <span class="keywordtype">void</span> SaveUserState();       <span class="comment">// save user-level register state</span></div>
<div class="line"><a name="l00153"></a><span class="lineno">  153</span>&#160;    <span class="keywordtype">void</span> RestoreUserState();        <span class="comment">// restore user-level register state</span></div>
<div class="line"><a name="l00154"></a><span class="lineno">  154</span>&#160;    AddrSpace *space;           <span class="comment">// User code this thread is running.</span></div>
<div class="line"><a name="l00155"></a><span class="lineno">  155</span>&#160;<span class="preprocessor">#endif</span></div>
<div class="line"><a name="l00156"></a><span class="lineno">  156</span>&#160;<span class="preprocessor"></span>};</div>
<div class="line"><a name="l00157"></a><span class="lineno">  157</span>&#160;</div>
<div class="line"><a name="l00158"></a><span class="lineno">  158</span>&#160;<span class="comment">// Magical machine-dependent routines, defined in switch.s</span></div>
<div class="line"><a name="l00159"></a><span class="lineno">  159</span>&#160;</div>
<div class="line"><a name="l00160"></a><span class="lineno">  160</span>&#160;<span class="keyword">extern</span> <span class="stringliteral">&quot;C&quot;</span> {</div>
<div class="line"><a name="l00161"></a><span class="lineno">  161</span>&#160;<span class="comment">// First frame on thread execution stack; </span></div>
<div class="line"><a name="l00162"></a><span class="lineno">  162</span>&#160;<span class="comment">//      enable interrupts</span></div>
<div class="line"><a name="l00163"></a><span class="lineno">  163</span>&#160;<span class="comment">//  call &quot;func&quot;</span></div>
<div class="line"><a name="l00164"></a><span class="lineno">  164</span>&#160;<span class="comment">//  (when func returns, if ever) call ThreadFinish()</span></div>
<div class="line"><a name="l00165"></a><span class="lineno">  165</span>&#160;<span class="keywordtype">void</span> ThreadRoot();</div>
<div class="line"><a name="l00166"></a><span class="lineno">  166</span>&#160;</div>
<div class="line"><a name="l00167"></a><span class="lineno">  167</span>&#160;<span class="comment">// Stop running oldThread and start running newThread</span></div>
<div class="line"><a name="l00168"></a><span class="lineno">  168</span>&#160;<span class="keywordtype">void</span> SWITCH(<a class="code" href="class_thread.html">Thread</a> *oldThread, <a class="code" href="class_thread.html">Thread</a> *newThread);</div>
<div class="line"><a name="l00169"></a><span class="lineno">  169</span>&#160;}</div>
<div class="line"><a name="l00170"></a><span class="lineno">  170</span>&#160;</div>
<div class="line"><a name="l00171"></a><span class="lineno">  171</span>&#160;<span class="preprocessor">#endif // THREAD_H</span></div>
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